Recently, introduction of WPAN (Wireless Personal Area Network) that constructs small wireless networks between a plurality of electronic devices existing in the human environment and performs information communication, has been considered.
Especially, as a technique of realizing ultra high speed radio communication, UWB (ultra wideband) has attracted attention.
UWB is a communication technique utilizing an ultra wideband and, in the standardization of FCC (Federal Communications Commission), is defined as radio communication having a fractional bandwidth (10 dB) equal to or greater than 20 percent of the center frequency or having a bandwidth equal to or greater than 500 MHz. Further, in the United States, 3.1 to 10.6 GHz of microwave bands are allowed to be used in UWB.
UWB uses short pulse signals on the order of nanoseconds, and, consequently, has characteristics of enabling high resolution performance at short range and high accuracy measurement.
Patent Document 1 discloses a ultra wideband signal transmitting/receiving apparatus and a method for enabling high speed, high capacity communication using the UWB more efficiently.
The ultra wideband signal transmitting/receiving apparatus and method disclosed in Patent Document 1 differs from existing UWB transmitting/receiving apparatuses in realizing efficient data transmission according to a channel condition by applying channel information acquired from a received signal to a transmitting section and changing a data transmission method according to the channel information in the transmitting section.
The ultra wideband signal transmitting/receiving apparatus disclosed in Patent Document 1 includes a receiving section that acquires channel information that allows UWB channel condition prediction using a UWB pulse signal received through a UWB channel, changes a data transmission method according to the acquired channel information and enables efficient data transmission according to the UWB channel condition, and can transmit and receive data efficiently by changing the data transmission method according to the UWB channel condition.
FIG. 11 illustrates a schematic view explaining general data transmission control operations between a UWB transmitting/receiving apparatus and a UWB transmitting/receiving terminal apparatus using ACK and NACK after data transmission in conventional UWB transmitting/receiving system.
As shown in FIG. 11, in this UWB transmitting/receiving system, first, the UWB transmitting/receiving terminal apparatus transmits a data request signal (step ST1101).
The UWB transmitting/receiving apparatus receives the data request signal from the UWB transmitting/receiving terminal apparatus and thereupon returns ACK (step ST1102).
After transmitting ACK, the UWB transmitting/receiving apparatus transmits data to the UWB transmitting/receiving terminal apparatus after predetermined time (step ST1103).
Here, when the propagation environment deteriorated after the UWB transmitting/receiving apparatus transmitted the data, the UWB transmitting/receiving terminal apparatus cannot receive the data correctly.
Therefore, in the conventional UWB transmitting/receiving system, when the propagation environment deteriorates and the UWB transmitting/receiving terminal apparatus failed to receive the data correctly, the UWB transmitting/receiving terminal apparatus returns NACK (step ST1104).
After receiving NACK returned from the UWB transmitting/receiving terminal apparatus, the UWB transmitting/receiving apparatus retransmits the data (step ST1105) and receives ACK from the UWB transmitting/receiving terminal apparatus so that data transmission is completed (step ST1106).    Patent Document 1: Japanese Patent Application Laid-Open No. 2004-336713